Information Technology Reference
In-Depth Information
Network Backup Approaches
In a network backup, one computer (or other device) typically
functions as the backup server—the machine to which your backup
drive(s) are physically connected. Files from your other machines
(which function as clients) are copied over the network onto each
backup drive. Network backups can proceed by four different methods:
•
Push:
The server shares its backup volume (using AFP, FTP, or
SMB), which the client machines mount as a volume in the Finder.
Then each client machine uses its own backup application to back
up files to the network volume (rather than to a locally attached
hard drive). This is sometimes called a
push
backup, as each client
“pushes” its data onto the network volume. If you use Time Machine
with a shared network volume or a Time Capsule, you're doing a
type of push backup.
•
Pull:
Each client machine shares its hard disk (again, using AFP,
FTP, or SMB). The server mounts these volumes in its Finder, and
then the backup application, running only on the server, copies files
from each network volume onto its locally attached backup volume.
This is sometimes called a
pull
backup, as the server “pulls” data
from each of the clients onto its backup volumes.
•
Client-server:
The server runs backup software that supports
client-server network backups, and the other machines run client
software that communicates with the server directly—without any
of the machines having to share or mount volumes. Retrospect is
the best-known example of client-server backup software.
•
Peer-to-peer:
Each computer on the network runs backup
software that can act as both a client (backing up that computer's
files to other computers) and a server (hosting the backed-up files
from other computers)—again, with no need to share or mount
volumes. When two or more computers use software that allows
mutual backups of this sort, it's called
peer-to-peer
backup.
CrashPlan is perhaps the best example of a program that supports
peer-to-peer backups.
